Rubber.



UNITED STATES PATENT oFrIoE.

DAVID SANIDMANN, 0F BERLiN, GERMANY.

RUBBER. 7

No Drawing.

To all whom it may concern:

Be it known that I, DAVID SANDMANN, a subject of the German Emperor, residing at Berlin, in the Empire of Germany, have invented certain new and useful Improvements in'Rubber; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in rubber.

I have discovered that a number of lactescent plant juices contain substances that can be coa ulated, such as the plant juices from whic rubber, gutta-percha, balata, and the like, can be obtained. Hitherto in the extraction of these substances difficulty has been experienced in bringin about a quick and complete separation of t e rubber, gutta-percha, or like substances from the milky juice. The usual method of dryin and smoking the same in a thin layer is di' licult and tedious, requiring Weeks and sometimes months before the rubber is ready for shipment. T have found that an excellent article can be produced by coagulatin the milky juice very quickly, and I have ound that certain acids and salts are very efiective for-this purpose, namely, acids and salts containin fluorin. Hydro-fluoric acid and Y acid fluorm compounds render it possible to position.

quickly separate the rubber, etc. from the juice or sap. At the temperatures which obtain in the countries where rubber, ttapercha and balata are extracted, the a ition of fiuorin-containing substances bi'ingsabout a pure fermentation of the sugar or similar su stances contained in the sap, so that these substances are converted and may be removed, while the rubber substance remains unaffected and is protected against decom- In carryin out the rocess of making rubher and simi ar artic es, the juice is mixed with a very dilute solution of hydrofluoric acid about per cent., and the mixture thoroughly stirred. After standing for some hours, the rubber separates on the surface in a layer, while the fermented substances remain in solution in the liquid. This layer of rubber may be easily removed from the liquid. The rubber is then placed in apress and the mixture contained therein squeezed out (althou h before this is done the rubber may be was ed, if desired). The rubber is Specification of Letters Patent. Patented Sept. 28, 1909- Application filed December 28, 1908. Serial No. 469,592.

a liter of crude sap, producing the separa-- tion referred to above. Similarly, potassium fiuorid, or sodium fluorid, or acid salts thereof, or silicic fluoric acid salts, as for example, silicic fiuorid of sodium, potassium or zinc can be used. These salts can. be

added to the sap in solid form and dissolved therein, or they can be used in solution.

Only a very small quantity of fluorin-containing substance is necessary to produce coa gulation. Moreover by this process it is possible to obtain rubber as an'inOdorous dry and elastic product ready for shipment, in a considerably shorter time than has hitherto been the case. Decomposition of the pectin and sugar-containing substances which are present in the sap is avoided. The removal of the water from the rubber by pressure can be effected in a few minutes, so that the finished roduct can be obtained in a single day, whereas by other \processes of drying in the .air or under heat, Iseveral weeks or even months were necessary. The product ob tained is of excellent quality, far 'superior to that obtained by former methods, being not contaminated with smoke-or other substances and having the matters foreign to the rubber almost completely removed. It is probable that the alcohol produced by the fermentation of the sugar aids in the coagulation of the rubber, and this fermentation in turn is greatly facilitated by the addition of a fluorin-containing substance.

The rubber thus obtained is very nearly pure. It is not discolored and is very salable. Its odor too is superior to that of ordinary rubber, there being an entire absence of putrefied substances and only avery small loss in the washing processes. One of "the most remarkable properties of this product is that it vulcanizes very much more rapidly than ordinary commercial rubber, and that when it is treated'with sulfur and litharge, as in the process of producing hard rubber, no part of the litharge is changed into sulfid of lead, as is sure to'happen under ordinary conditions. I The affinity of the rubber to the sulfur, in other words, exceeds the affinity of the sulfur. for the lead JXld, and it is thus possible to make hard rubber by the use of sulfur and litharge, which product does not which are liable to decomposition; and leavof lead. The reason for this extraordinary I aflinity of the rubber for sulfursis difiicult'to state, although the fact is well known. It is robably due to the'fact that the rubber prouced is very quickly coagulated and sep- =arated from all the other substances contained in the sap, makin a product which has a high aflinity for sul ur and which when, treated with sulfur isf-less liable to the at tacks of oxygen. That is to say, owing to the quick fermentation, the rubber is quickly separated without separatin therefrom the resins, but separating there rom other foreign substances, such as pectin, sugar, etc.,

ing the resins in an acid condition in which they-possess a strong aflinity for sulfur. v The presence of the, small quantities of fluoric acid or other fiuorin compounds has 20 :1 conserving quality on the rubber, and affords means to distinguish the new rubber from all the rubbers on market till now.

. I claim:-

As a new article of manufacture, a hard-25 rubber-produced by coagulating the sap by a fluorin-containing substance, said coagulated product being pressed and vulcanized under heat with amixture of sulfur and lithar e the roduct bein elastic, inodorous 3 0 g a P g and containing no ap reciable quantity of sulfid of lead, substantially as described.

In testimony whereof, I afiix my signature, in presenceof two witnesses. DAVID SANDMANN.

Witnesses: 1

HENRY HASPER, 'WoLnEMAR HAUPT. 

